1. Field of the Invention
The present invention relates generally to automotive vehicle occupant restraint systems, particularly air bags. It relates more specifically to mechanisms for disabling such systems selectively.
2. Description of the Related Art
Since inflatable occupant restraint systems or air bag systems have come into widespread use in the automotive industry, it has been observed that there are certain instances in which it may be desirable to disable operation of the air bag system in a vehicle during the period in which the vehicle is in use. Exemplary of such instances is that present when a vehicle has air bags for both the driver and passenger positions and a rear facing infant seat is placed in the passenger position and is not properly positioned for use with the air bag. Since practically all air bag systems presently in use are activated by transmitting an electrical signal powered by the vehicle electrical system to an igniting device in the air bag system, it has been suggested to provide switching to effect disabling of the air bag system on a selective basis. U.S. Pat. Nos. 5,324,074; 5,234,228; and 5,161,820 are exemplary of such approaches.
Certain disadvantages, however, are noted in the prior art disabling systems. These disadvantages arise from the appropriate desire of the designer of the occupant restraint system to ensure that because of the inherent normal benefit of having the air bag system operating, the disabling takes place only when intended and only under the control of the operator of the vehicle. It is also desired that the reliability and efficacy of this disabling device be monitored during a vehicle operating event which might normally give rise to operation of the air bag disabled by the disabling system. None of the prior art devices provide such advantages.
In response to the disadvantages of the prior art disabling systems, the present invention provides an air bag disabling system for use in automotive vehicles having an air bag mounted in the instrument panel of the vehicle and electrically connected to the electrical power system of the vehicle for activation response to a condition sensed by an acceleration sensor mounted in the vehicle which includes a switch electrically connected to the vehicle power source into the air bag and selectively movable between a first position interconnecting the source of electrical power and the air bag to enable activation of the air bag and a second position providing such activation, and a resistive test load substantially equivalent to the resistive load of the air bag connected in parallel with the air bag in series with the switch.
According to one feature of the present invention, a fuse is connected in series between the resistive test load and the switch configured to break connection upon sensing a level of current through the switch equal to that required to activate the air bag.